Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1235302 | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2008 | 6 Pages |
Model aliphatic polyurethane (APU) hard segment based on 1,6-hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) were prepared. FTIR and molecular mechanics (MM) simulation were used to conduct the systematic studies on APU and polyamide-66 (PA-66) whose sole difference lies in the alkoxyl oxygen. It was found that the introduction of the alkoxyl not only increases the conformations in APU, makes it a possible H-bond acceptor, but also weakens the H-bond between NH and OC in APU. There are two conformers stably existed in APU with lowest energy, leading to eight H-bond complexes based on NH as donor and (1) OC as acceptor, and another two complexes based on (2) alkoxyl O and (3) urethane N as acceptors, whereas there is only one stable conformer in PA-66, leading to one H-bond complex. One predominant H-bond complex has been found in APU with probability of about 95%. The simulated results are consistent with the νNH and νCO band shifting in FTIR.